Year-Long Measurement of Glucose Oxidase Deactivation in Electrochemical Glucose Sensors

The long-term in-vitro performance and stability of an electrochemical glucose sensor based on glucose oxidase were evaluated over one year. Ageing experiments designed to maintain the glucose oxidase in an oxidised state demonstrated a sensor response which decayed exponentially, with a half-life of 75 days. As the sensor aged, the rise-time in response to a glucose step was found to progressively increase, which is attributed to the glucose needing to diffuse further into the sensor's polymer membranes to reach active enzyme. These results represent the first measurement of the decay of glucose oxidase enzyme for a year-long period. The results provide updated and higher-confidence glucose oxidase deactivation rates, support the feasibility of long-lifetime implantable continuous glucose monitors, and highlight design considerations for enabling the next generation of accurate and low-burden glucose monitoring technologies.